Typically, stuffing of casing is accomplished by gathering a length of the casing on to a stuffing horn. The foodstuff is then pressed through the horn and into the casing which is stuffed and drawn forward off the horn.
Casings most commonly used are made of regenerated cellulose and generally are of two types. Small size unreinforced cellulosic casing is used for the production of frankfurters and the like. Large size fibrous reinforced cellulosic casing is used for the production of larger diameter products, such as bologna and hams.
It is customary in the art to utilize casing in the form of hollow shirred sticks. A shirred stick is composed of a relatively long length of casing shirred and longitudinally compacted to a relatively short length. For example, a shirred stick 50 centimeters long may contain upwards to 50 meters of casing. Shirred sticks are preferred in automatic stuffing operations because the stuffing cycle, once started, can continue uninterrupted until the entire length of casing is stuffed. In conventional use, the shirred stick is slipped over the stuffing horn so that the horn extends through the entire length of shirred stick. This requires that the bore of the stick be relatively straight and have a diameter large enough to accomodate the passage of the horn through the stick.
It is well known in the art that the ratio of the length of casing contained by the stick to the length of the stick (hereafter referred to as pack ratio) depends in part on the bore size of the stick. In particular, pack ratio varies inversely to the bore diameter of the stick.
Packing houses usually prefer to use a stuffing horn having as large a bore diameter as possible. This maximizes the flow rates through the horn and increases productivity. As large a bore diameter as possible also is better for foodstuff that tend to form aesthetically undesirable grease and fat deposits at the casing/foodstuff interface.
The shirred stick must have a bore diameter larger than the stuffing horn diameter in order to provide the clearance needed for placing the stick on the stuffing horn. Thus, the desirable stick feature of high pack ratio is compromised by the desirability of having a stuffing horn as large in diameter as possible for any given size of casing. Accordingly, the length of casing contained in a stick supplied to the packing house is dictated in part by the length and the diameter of the stuffing horn used by the packing house.
Ways are continuously being sought to satisfy the conflicting objectives of increasing the stick pack ratio while maintaining a bore diameter able to accomodate the largest possible stuffing horn. For example, manufacturers of casing articles have improved shirring and compaction methods so as to increase the length of casing contained in the stick while maintaining the largest bore diameter possible. Manufacturers of stuffing apparatus tend to make the stuffing horn wall as thin as possible to maximize the inside diameter of the horn. As a result, horns of conventional stainless steel, now used for stuffing small diameter casings, have such thin walls that they are easily damaged. Meat packers cope with this problem by maintaining an inventory of stuffing horns in a variety of sizes and by changing horns so that the largest possible horn in used with any given casing stick.
Another solution to this problem is disclosed in U.S. Pat. Nos. 4,467,499; 4,540,300 and 4,627,130. These patents each disclose a casing article comprising a length of shirred and highly compacted casing positioned on a disposable stuffing horn. The highly compacted casing grips tightly about the disposable stuffing horn so that the friction between the casing and the horn holds the casing at an enhanced pack ratio. The pack ratio of these articles is further enhanced by elimination of the clearance space otherwise needed to permit the user to slip the shirred casing onto the stuffing horn.
Accordingly, it is an object of the present invention to provide a stuffing method and apparatus which opens the full bore diameter of a shirred stick to product flow and eliminates the need to occlude of otherwise restrict the diameter of the stick bore by positioning a stuffing horn within the stick bore.
Another object of the present invention is to provide a stuffing method and apparatus which eliminates the need for the meat packer to maintain stuffing horns of different sizes in inventory.
A further object of the present invention is to provide a stuffing method and apparatus which permits the casing manufacturer to provide more casing in a shirred stick without decreasing the size of the bore diameter required for efficient stuffing.